The present invention relates to an automatic transmission controller for venting air from a frictional engagement member of an automatic transmission.
Japanese Patent Application Publication No. 2007-205518 discloses a technique for venting air from a first frictional engagement member of an automatic transmission by applying the first frictional engagement member and releasing a second frictional engagement member of the automatic transmission, wherein the first frictional engagement member is released and the second frictional engagement member is applied when in P range (parking range). This air vent is implemented by repeatedly supplying hydraulic pressure to the frictional engagement member until a time period for which the hydraulic pressure is supplied to the first frictional engagement member reaches a predetermined reference period of time, thereby venting air that remains in a hydraulic circuit system configured to supply hydraulic pressure to the frictional engagement members.